class C {
  constructor(name) {
    this.name = name
  }
  print() {
    console.log('this is C',this.name)
  }
}
class D extends C {
  constructor(name,age) {
    super(name)
    this.age = age
    this.init = function() {
      console.log('init D')
    }
  }
  sayHi() {
    let a = {A: 'A'}
    const b = {B: 'B'}
    const c = 'c'
    console.log(a,b,c)
    console.log('this is D',`${this.name}:${this.age}`)
  }
}

export const instance2 = new D('llb',20)